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STRUCTURAL ALTERATIONS OF AMINO ACIDS AT THE LEVEL OF AMINOACYL‐tRNAS: TRANSFORMATION OF DICARBOXYLIC AMINO ACIDS
Author(s) -
Roux Huguette,
Murthy M. R. V.
Publication year - 1975
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1975.tb03893.x
Subject(s) - amino acid , chemistry , asparagine , biochemistry , glutamine , transfer rna , rnase p , aminoacylation , aminoacyl trna , stereochemistry , rna , gene
— Radioactive glutamate, glutamine, aspartate and asparagine were incorporated into calf brain tRNA in the presence of homologous aminoacyl‐tRNA synthetases. When the aminoacyl‐tRNAs were deaminoacylated and the products chromatographed in the phenol solvent, the glutaminyl‐and asparaginyl‐tRNAs showed two products GnP 2 and AnP 2 respectively, in‐ addition to the original amino acids. These new substances moved close to the solvent front in contrast to glutamine and asparagine which had much lower R F values. Attachment of the amino acids to tRNA appeared to be a prerequisite for the formation of these substances, since they were not found in the reaction mixture used for aminoacylation in the absence of incubation or on omission of tRNA or when tRNA was degraded by RNase. Application of the deaminoacylation procedure to pure amino acids also failed to lead to their formation. In an other series of experiments, the dicarboxylic aminoacyl‐tRNAs were hydrolysed with pancreatic RNase and then analysed by high voltage paper electrophoresis. Again, the glutaminyl‐ and asparaginyl‐tRNAs showed two new components, GnE 3 and AnE 3 , in addition to the expected glutaminyl‐ and asparaginyladenosines. GnE 3 and AnE 3 exhibited much faster electrophoretic mobilities in the direction of the cathode than the adenosine derivatives of the original amino acids and thus appeared to be more positively charged. The presence of these new compounds in the products of deaminoacylation or in R Nase hydrolysates was specific to glutaminyl‐ and asparaginyl‐tRNAs and did not occur in the case of either glutamyl or aspartyl‐tRNAs, indicating that the amide group was probably involved in the transformation reaction.